Cochlear implant systems typically use pulse amplitude modulation to encode loudness. In other words, a loudness level of an audio signal presented to a cochlear implant patient may be represented to the patient by modulating (e.g., setting) an amplitude of a stimulation pulse that is applied to the patient (e.g., by way of an intracochlear electrode). To illustrate, a cochlear implant system may represent a relatively low loudness level by applying a stimulation pulse that has a relatively low amplitude and a relatively high loudness level by applying a stimulation pulse that has a relatively high amplitude.
The maximum amplitude that any given stimulation pulse may have is governed by the compliance voltage associated with a cochlear implant included within the cochlear implant system. For example, if the compliance voltage is represented by V and the impedance of the tissue associated with an electrode is represented by R, the maximum current (represented by Imax) that may be applied by way of the electrode is defined by Ohm's law in the following equation: Imax=V/R. 
Unfortunately, conventional cochlear implant systems cannot adjust the compliance voltage in an instantaneous manner to guarantee efficacy of stimulation while minimizing power consumption. In other words, with pulse amplitude modulation, the compliance voltage is typically set to achieve the largest stimulation pulse amplitude in a window of time (e.g., a stimulation frame) as opposed being dynamically adjusted during the window of time to match the amplitudes of individual stimulation pulses. This may result in power consumption inefficiencies, which, in turn, may adversely require a relatively large power source (e.g., battery).
Pulse width modulation has been proposed as a potential alternative to pulse amplitude modulation. Pulse width modulation offers the advantage of minimizing losses due to compliance voltage mismatch between what is required and what is maintained. However, pulse width modulation is difficult to implement and may suffer from limited dynamic range and resolution issues. For example, the relationship between loudness and charge delivered using pulse width modulation may not have a large enough dynamic range for pulse width modulation to be efficacious.